Application FR-2 939 711 in the name of the applicant company discloses a support for assembling a green tyre blank. The support comprises a baseplate of cylindrical overall shape which on its circumference bears mutually identical shaping members. Each member comprises a series of external elements mounted with the ability to slide independently of one another with respect to a base of the member in a direction radial to the axis of the baseplate. The circumferential external faces of the elements form a support surface on which to assemble the components used to build the green tyre blank. The position of each element with respect to the base is defined by slipping into the member a cam against which the elements press while occupying the required position. The cam has a curvature identical to the curvature that is to be imparted to the surface supporting the green tyre blank. If the shape of this surface is to be changed, for example by accentuating or reducing the curvature, each cam is replaced with a cam that has the required shape. This tyre-building support is therefore a variable-geometry support and can be used by itself to assemble different types of green tyre blank intended for the manufacture of different types of tyre.
However, improvements to this support are still being sought. This is because the abovementioned way of mounting the mobile elements gives the curved bearing surface a stepped profile with corner edges that protrude slightly as seen in a plane radial to the support. Now, it is on this profile that the plies of raw rubber are directly laid, these plies being relatively fragile and therefore carrying the risk of becoming damaged.